Pneumatic jack

ABSTRACT

A pneumatic jack comprising a telescopically extendable lifting axis which is enclosed by a flexible bellows, the lifting axis having five stages extendable telescopically with a first stage thereof being mounted on a rollable base plate, and at least the third and fourth stages of said lifting axis having a checking means for limiting movement of said latter stages into one another.

United States Patent 1191 v 1111 3,743,248 Moor July 3, 1973 [54] PNEUMATIC JACK 2,803,224 8/1957 Wilson 92/53 1,711,565 5/1929 Hatfield 92/53 X [761 Invent "'2'" K 4805 3,298,664 H1967 Dixon 254/93 R Emma", Switzerland 3,279,755 10/1966 Notenboom. 254/93 R I 2,805,839 9/1957 Branick 254/93 HP [22] 1970 2,070,960 2/1937 Phillips 254/93 HP [21] Appl. No.: 86,136

Primary Examiner-Othell M. Simpson [30] Foreign Application Priority Data A'wmey Raymnd Rob:

Apr. 15, 1970 Switzerland 5647/70 BS ACT [52] US. Cl. 254/93 R A pneumatic jack comprising a telescopically extend- [51] Int. Cl B66f 3/24 a le i ing axis which is enclosed y a flexible l [58] Field of Search 254/93 R, 93 H, 93 HP; the lifting axis having five stages extendable telescopi- 92/53; 91/169 cally with a first stage thereof being mounted on a rollable base plate, and at least the third and fourth stages [56] References Cit d of said lifting axis having a checking means for limiting UNITED STATES PATENTS movement of said latter stages into one another. 1,917,011 7/1933 Bird 9l/169X 6 Claims, 2 Drawing Figures The present invention relates to a pneumatic jack which has a telescopically extendable lifting axis and which is enclosed by a rubber bellows.

Motor vehicle repair workshops or motor vehicle service stations use jacks with which one side, the wheel axle or only an individual wheel of a motor vehicle can be raised. It is known to use mechanical jacking devices for this purpose. These devices, however, have the disadvantage that they are either constructed too weak so that with constant use they fail to work, or that they require too much space so that where space is restricted these devices cannot be employed. This is particularly true when a motor vehicle which is parked between two vehicles parked closely together has to be raised.

The above named difficiencies can be overcome by pneumatic jacks which in themselves require little space and are yet constructed sufficiently strongly and robustly, that they can withstand relatively large stresses. Pneumatic jacks are known, which have a telescopically extendable lifting axis which is enclosed by an elastic bellows. The lifting axis of these jacks consist of three stages which are telescopically extendable. The disadvantage of these known jacks resides in the fact that, when the air is let out, the uppermost stage is lowered too early into the middle stage and in so doing can lock or jam in this middle stage so that the process of lowering the vehicle is impaired or made quite impossible. This must be counted as a disadvantage in a repair workshop where work must be carried out in good time, since the economic use of these jacks cannot be fully ensured.

A further disadvantage of the known pneumatic jack is the fact that the latter is not constructed to be transportable so that its movement from one working place to another is rendered difficult.

The present invention aims at the provision of a jack which does not have the above-mentioned disadvantages.

The present invention consists in a pneumatic jack comprising a telescopically extendable lifting axis which is enclosed by a flexible bellows, the lifting axis having five stages extendable telescopically with a first stage thereof being mounted on a rollable base plate, and a least the third and fourth stages of said lifting axis having a checking means for limiting movement of said latter stages into one another.

The invention will now be particularly described, by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a diagramatical view of the jack according to the invention.

FIG. 2 is a longitudinal section through the lifting axis of the jack.

In FIG. 1, two rollers 11 are pivotably arranged on one of the wide sides of a base plate 10. These rollers 11 are supported in carriers which extend away from the support surface of the base plate in such a manner that the running surface of these rollers 11 come into contact with the ground only at an inclination of the base 10 of about 45. With the base plate 10 set down on the ground the running surfaces of the rollers 11 are in this way not in contact with the ground. A guide handle 12 with a handgrip 13 is secured to the base plate 10. Furthermore there is attached to this base plate 10 a flange member 14 (FIG. 2) to which the first, that is to say the hollow lowermost stage 15 of the lifting axis of the jack is secured. Secured to the flange member 14 is one end of an air supply hose 16 the other end of which is secured to a hook 17 attached to the guide handle 12. This end is then connected, when using the jack, to a compressor by means of a suitable member. The hollow second stage 18 of the lifting axis is arranged to slide in the first stage 15. An annular internal projection 19 on the upper edge of the stage 15 serves as stop for the second stage 18 which has an internal annular projection 20 on its lower edge. When the lifting axis is extended the projection 20 strikes against projection 19 on the stage 15 to limit the outward movement of stage 18. In the second stage 18 is arranged slidably a third stage 21, in this a fourth stage 22, and in this a pin 23 serving as fifth stage. The said third and fourth stages are also provided with stopping means equivalent to projection 19, 20 which have been explained in detail in the description of the first and second stages. On each of the annular projections 19 of the third and fourth stages there is arranged a checking means in the form of a Seger ring 24. In the present case these Seger rings ensure the uniform sliding into each other of the individual stages when the air is discharged. When the lifting axis sinks, the Seger ring 24 of the fourth stage 22 touches down on the upper edge 25 of the third stage 21 before the stage 22 can quite penetrate the third stage 21 and jam therein. The tendency to jam is particularly dangerous when the lower stages have not yet begun to slide into each other. The described effect is also achieved-by the Seger ring 24 of the third stage 21, which ring impinges upon the upper edge 26 of the second stage 18 when the air is discharged.

The individual stages 15, 18, 21, 22 and 23 are manu factured from steel tubing with a wall thickness of about 5 mm. This wall thickness gives the jack sufficient stability so that any tipping of the same is almost excluded.

To the upper end of the fifth stage 23 a flange member 27 is secured by means of screws, which flange member serves support a surface of the vehicle to be lifted. To the upper flange member 27 a rubber bellows 28 is attached which serves as casing for the five stages of the lifting axis. The length of the bellows 28 isdetermined in such a manner that when the stages are extended telescopically they are enclosed by the bellows and are protected by it against soiling and damage. A lower end heading of the bellows can be secured to the lower flange member 14, for example by screws or clamping means. a

A safety valve arranged on the lower flange member 14 is given the reference numeral 30. Since the use of such valves in pneumatic appliances is known in general, the manner of working of this valve known per se will not begone into any more detail here.

The described pneumatic jack is rendered operative by actuation of the air. inlet valve 29 at and of the hose 16. A lifting capacity of 1.5 t/Ss is achieved with a pressure of 6 atmospheres absolute excess. The extended jack reaches a height of about 37 cm, while in the collapsed state its height is still only about 16 cm. The jack can be applied to the side, at the wheel axle or in the vicinity of an individual wheel of the motor vehicle.

In order to render possible certain angular settings when applying the jack to the motor vehicle to be lifted, it is conceivable to secure the upper flange member 27 pivotable to the pin 23. The upper flange member 27 could also be arranged firmly, but for this purpose it ought to have a flexible support which, for its part, would render possible application of the jack in a certain angular position.

I claim:

1. A portable pneumatic jack comprising a telescopically extendible lifting assembly and a flexible bellows enclosing said lifting assembly, the lifting assembly having five stages telescopically engaged one into the other and adapted to slide thereinto, a rollable base plate for supporting said member, said base plate defining means for resting on a support surface during use and be rollable when not in use the first lower stage being fixed to the said plate, a groove provided around the periphery of at least the upper third and fourth stages, said groove being located below the outer upper edge, and a ring disposed in each of said grooves, wherein the ring is adapted to rest on the upper surface of the next lower stage before the said third and fourth stages reach their lowermost position relative to the respective next stages position.

2. A pneumatic jack as claimed in claim 1, wherein the four lower stages are constructed of steel tubing, while the uppermost stage consists of a pin, and the four lower stages are each provided with an internal upper projection which, when the stages are extended, is caused to come into contact with an internal lower projection of the next higher stage to limit outward relative movement of said stages.

3. A pneumatic jack as claimed in claim 1, wherein the checking means comprises a Seger ring attached to the upper end of the outer casing of the third and fourth stages and which, when the stages slide into each other, strike against the upper edges of the third and second stages respectively.

4. A pneumatic jack as claimed in any of claim 1 wherein two rollers are pivoted at one wide side of the base plate in such a manner that when the base plate is set on the ground the running surfaces of these rollers do not touch the ground.

5. A pneumatic jack as claimed in claim 4 wherein to the base plate is secured a guide handle which has securing means for the free end of an air supply hose.

6. A pneumatic jack as claimed in claim 5, wherein the other end of the air supply hose is attached to a flange member secured to the base plate, in which flange member there is additionally arranged a safety valve. 

1. A portable pneumatic jack comprising a telescopically extendible lifting assembly and a flexible bellows enclosing said lifting assembly, the lifting assembly having five stages telescopically engaged one into the other and adapted to slide thereinto, a rollable base plate for supporting said member, said base plate defining means for resting on a support surface during use and be rollable when not in use the first lower stage being fixed to the said plate, a groove provided around the periphery of at least the upper third and fourth stages, said groove being located below the outer upper edge, and a ring disposed in each of said grooves, wherein the ring is adapted to rest on the upper surface of the next lower stage before the said third and fourth stages reach their lowermost position relative to the respective next stages'' position.
 2. A pneumatic jack as claimed in claim 1, wherein the four lower stages are constructed of steel tubing, while the uppermost stage consists of a pin, and the four lower stages are each provided with an internal upper projection which, when the stages are extended, is caused to come into contact with an internal lower projection of the next higher stage to limit outward relative movement of said stages.
 3. A pneumatic jack as claimed in claim 1, wherein the checking means comprises a Seger ring attached to the upper end of the outer casing of the third and fourth stages and which, when the stages slide into each other, strike against the upper edges of the third and second stages respectively.
 4. A pneumatic jack as claimed in any of claim 1 wherein two rollers are pivoted at one wide side of the base plate in such a manner that when the base plate is set on the ground the running surfaces of these rollers do not touch the ground.
 5. A pneumatic jack as claimed in claim 4 wherein to the base plate is secured a guide handle which has securing means for the free end of an air supply hose.
 6. A pneumatic jack as claimed in claim 5, wherein the other end of the air supply hose is attached to a flange member secured to the base plate, in which flange member there is additionally arranged a safety valve. 